The 18NLW4500 is a 18" (466 mm) extended low frequency loudspeaker, designed for use in vented, bandpass or even horn loaded ì enclosures. The loudspeaker is designed to withstand high power levels without damage while providing clean and undistorted LF reproduction at a very high SPL. For optimum results we recommend amplifiers able to deliver 3600 Watt program power. The 18NLW4500 features a unique motor featuring a high grade Neo magnet assembly in a structure optimized for thermal and magnetic efficiency. 18NLW4500 features include a large displacement suspension system which, in conjunction with a composite reinforced, straight ribbed cone and the Eighteen Sound proprietary SDR technology, allows an undiostorted ultra-linear piston action and provides full mechanical control across the entire working range. The 115mm (4.5 in) state-of-the-art voice-coil utilizing Interleaved Sandwich Voice coil (ISV) technology, provides high levels of thermal stability and durability. The ISV technology achieves a balanced linear motor unit exerting an exceptionally high force factor.